1. Field of the Invention
The invention relates generally to agricultural equipment, such as harvesters, and more specifically, to spreader arrangements on such harvesters for spreading agricultural material to a field.
2. Description of the Related Art
An agricultural harvester known as a “combine” is historically termed such because it combines multiple harvesting functions with a single harvesting unit, such as picking, threshing, separating and cleaning. A combine includes a header which removes the crop from a field, and a feeder housing which transports the crop matter into a threshing rotor. The threshing rotor rotates within a perforated housing, which may be in the form of adjustable concaves and performs a threshing operation on the crop to remove the grain. Once the grain is threshed, it falls through perforations in the concaves onto a grain pan. From the grain pan, the grain is cleaned using a cleaning system, and is then transported to a grain tank onboard the combine. A cleaning fan blows air through the sieves to discharge straw, chaff and other debris toward the rear of the combine.
During the process of harvesting, crop material other than grain is intended to be expelled from the combine. This material is usually derived from one of two areas, the threshing rotor or the cleaning system. The material expelled from the threshing rotor is generally referred to as straw and the material expelled from the cleaning system is generally referred to as chaff. This material or crop residue is typically dealt with by spreading or windrowing.
Spreading is accomplished using a mechanical device termed a spreader to distribute the straw and/or chaff substantially evenly from the rear of the combine. This spread material is usually chopped to as short a length as possible so that when it is spread it will break down as quickly as possible and not interfere with tillage or seeding operations.
Often, different field conditions require different apparatuses to spread the residue the full width of the head evenly. Many spreaders can adjust the speed of the spreading device to change the distance that material is spread. However, changing speed greatly affects the distribution of the spread. For instance, as the speed is slowed to spread to a narrower width, the material in the center increases without an adjustment point to change the distribution.
Conventional deflectors can be placed on the outside of the spreaders. These deflectors can pivot laterally to restrict the area in which that material can be spread, but they often cause an uneven spread. Moreover, material distribution fluctuates with the speed of the spreader. Some conventional designs incorporate a center mounted deflector that slides up and down to control the amount of material in the center of the spread while using deflectors in the center to influence the distance of the spread. Unfortunately, a sliding joint can also inadvertently accumulate crop material.